Fix FLANN python bindings #24028
As a side-effect this patch improves reporting errors by FLANN `get_param`.
resolves#21642
### Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake
* Clean: make the use of the indices array length consistent
Either we don't want this method to be used in the future for any other node
than the root node, and so we replace indices_length by size_ and remove it as
argument, or we want to be able to use it potentially for other nodes, and
so using size_ instead of indices_length would have lead to a bug.
* Fix: b was not an address
* Fix: transpose the Flann repo commit "Fixes in accum_dist methods" from Adil Ibragimov
Avoids trying to compute log(ratio) with ratio = 0
* Fix: transpose the Flann repo commit "result_set bugfix" from Jack Rae
* Fix Jack Rae commit as the initial i - 1 index was decremented before entering the loop body
* Clean: transpose the Flann repo commit "Updated comments in lsh_index" from Richard McPherson
* Fix: Transpose the Flann repo commit "Fixing unreachable code in lsh_table.h" from hypevr
* Fix warning the same way it was done in flann standalone repo
* Change the return value in case of unsupported type
